Breaker arm assembly for a contact set



Oct. 18, 1966 v. E. HEIL 3,280,292

BREAKER ARM ASSEMBLY FOR A CONTACT SET Filed April 8. 1965 INVENTORVERNON E. HE/L BY I) ATTORN Y United States Patent 3 280,292 BREAKER ARMASSEMBLY FOR A CONTACT SET Vernon E. Heil, Indianapolis, Ind, assignorto P. R. Mailory & Co. Inc., Indianapolis, 11141., a corporation ofDelaware Filed Apr. 8, 1965, Ser. No. 446,489 8 Claims. (Cl. 200-166)The present invention relates to periodic circuit breakers, and moreparticularly relates to circuit breakers used by ignition timers forinternal combustion engines.

A prime consideration in timer systems is to provide contact breakerswherein the alignment of contacts during the operation of the system ismaintained substantially without variation and wherein any undesirablevariation in eifectively rotationally centering the contact arm aboutits pivot post during the process of opening and closing contacts isavoided.

In the several types of circuit breaker systems heretofore constructed,certain disadvantages have been found. For example, in pivoted breakertype systems, there is the disadvantage that any radial clearance in thepivot bearing used in the breaker allows an undesirable variation in therelative alignment of the two contacts during operation. To keep theseclearances within reasonable limits at all temperatures over areasonable lifetime is an exacting problem of design and production, foras the life of the contacts progresses, surface irregularities developon the contacts. Normally, one contact becomes pitted and the othercontact develops a projection of deposited metal. If these do not alwaysmate exactly, both the performance and the life of the contacts :areadversely affected.

In an attempt to overcome the alignment difficulty, a type of contactorknown as the pivotless contactor has been devised wherein a contact armis held and located by a flat leaf spring. Because there is no lostmotion or friction in the spring itself, there is commonly no difficultyexperienced with relative alignment of contacts. However, there areoften undesirable variations in the effective center of rotation of thecontact arm during the process of making or breaking contact. Thiseffect is likely to be most pronounced at high speeds where inertiaforces are relatively large in comparison with static forces. To combatthis result, the effective length of the spring is made very short. Theshortening of the spring results in highly concentrated stresses in thespring and necessitates very exacting tolerances of forming to maintainproper contact pressure.

It is therefore an object of the present invention to provide a novelignition contact breaker having a construction which provides exactcontact alignment for the breaker and wherein said breaker may be madeto rotate around a fixed axis so as to provide for an improved highspeed ignition contact make and break system.

It is an object of the present invention to provide a durable ignitioncontact breaker which operates at high speeds with a minimum ofchattering or rebounding.

It is an object of the present invention to provide a means foreliminating play in the pivot arm about the pivot post in order toreduce the spurious oscillations and contact bounce and thus improvebreaker performance.

The invention, in another of its aspects, relates to novel features ofthe instrumentalities described herein for teaching the principal objectof the invention and to the novel principles employed in theinstrumentalities whether or not these features and principles may beused in the said object and/ or in the said field.

Other objects of the invention and the nature thereof will becomeapparent from the following description considered in conjunction withthe accompanying figures of the drawing and wherein the scope of theinvention is determined rather from the dependent claims.

Referring now to the drawings:

FIGURE 1 is a perspective view of the ignition breaker;

FIGURE 2 is a sectional view of the breaker taken through section 22 ofFIGURE 1;

FIGURE 3 is a sectional view of the pivot construction taken throughsection 33 of FIGURE 2;

FIGURE 4 is a perspective view of the pivot bushing.

Generally speaking the present invention provides a durable ignitionbreaker which operates :at high speeds with greatl improved contactchattering or rebound characteristics. To accomplish this, a nylon pivotarm having an integrally formed pivot bushing is utilized. The bushingis slit in the section around the pivot hole or opening, :and a springclip is positioned around the outside of the pivot bushing to force thebushing against the pivot post. This permits a close fit at the pivotpost and eliminates the danger of binding because of compliance. Thebreaker gives better high speed performance and longer contact life thanpresent breakers because of the improved dwell characteristics :andlower contact bounce.

In FIGURE 1, circuit breaker 10 comprises a nylon arm 11 having camfollower 12 and pivot bushing 13 integrally formed therewith. Bushing 13has aperture 14 (FIG. 4) for pivot post 15 (FIG. 2). Bushing 13 has slit16 to permit a close fit around post 15 but to prevent binding. Springclip 17 is positioned around the outside of bushing 13 to force thebushing against post 15. Tension spring 18 is secured to arm portion 11by rivets or eyelets 19, 20, 21 [and 22, and is fastened to bracket 23by fastening means 24 which also provides an electrical termination.Contact arm 25 also is secured to nylon arm 11 by rivets or eyelets 19,20, 21 and 22 and has a movable contact 26 at one end thereof.Stationary contact 27 is mounted to ear portion 28 of bracket 23 inalignment with movable contact 26. The point opening of the contacts is:between 0.014 and 0.020 inch.

In FIG. 2, it can be seen that bushing 13 of arm 11 is fitted aroundpost 15. Slit 16 provides for compliance in the walls of the bushing 13which, in connection with the spring clip 17, minimizes the distancebetween the bushing and the post thereby controlling spurious, unwantedmovements of the contact arm about the post. Clip 17 forces bushing 13against post 15, thereby permitting a close but not binding fit.

FIGURE 3 is a sectional View taken through section 33 of FIGURE 2showing the pivot post 15 surrounded by bushing 13. Spring clip 17forces bushing 13 against post 15 which is mounted to bracket 23. Therelationship of spring clip 17 and split bushing 13 is shown in FIGURE4.

The present invention eliminates play in the breaker arm pivot therebyeliminating variation in the contact location. The close fit of thenylon bushing to the pivot shaft limits the movement of the contact armto rotational movement. Thus chattering and rebounding of contacts isprevented.

The embodiment of the present invention as hereinabove described isillustrative and not exhaustive in scope, and since many widelydiffering embodiments may be made without departing from the scope ofthe present invention, it is intended that all matter contained in theabove description and shown in the accompanying drawing shall beinterpreted as illustrative and not in a limiting sense.

Having thus described my invention, I claim:

1. In an ignition breaker, a pivot arm comprising: a non-conductive armportion having a first end and a second end; said first end terminatingin a split bushing, said split bushing circumferentially engaging apivot post; resilient means urging said split bushing against said pivot3 post; said split bushing adapted to pivotally support said pivot armon said pivot post; said second end terminating in a cam follower, saidcam follower extending downwardly from said pivot arm; and a conductivearm portion cooperating with said non-conductive arm portion.

2. In an ignition breaker, a pivot arm comprising: a nylon arm portionhaving a first end and a second end; said first end terminating in asplit bushing, said split bushing circumferentially engaging a pivotpost; resilient means urging said split bushnig against said post; saidsplit bushing adapted to pivotally support said pivot arm on said post;said second end terminating in a cam follower, said cam followerextending downwardly from said pivot arm; and a conductive arm portioncooperating with said nylon arm portion. 1

3. In an ignition breaker, a pivot arm comprising: a nylon arm portionhaving a first end and a second end; said first end terminating in asplit bushing, said split bushing circumferentially engaging a post; aclip spring urging said split bushing against said post; said splitbushing adapted to pivotally support said pivot arm on said post; saidsecond end terminating in a cam follower, said cam follower extendingdownwardly from said pivot arm;

and a conductive arm portion cooperating with said nylon arm portion.

4. In an ignition breaker, a pivot arm comprising: a nylon arm portionhaving a first end and a second end; said first end terminating in asplit bushing; said split bushing circumferentially engaging a post;resilient means urging said split bushing to said post; said splitbushing adapted to pivotally support said pivot arm on said post; saidsecond end terminating in a cam follower, said cam follower extendingdownwardly from said second end; a conductive arm portion aflixed to atop surface of said nylon arm portion, said conductive arm portionextending outwardly beyond said nylon arm portion and terminating in amovable contact; a leaf spring having one end affixed to a bottomsurface of said nylon arm portion, said leaf spring being looped aroundsaid bushing in a spaced relationship therewith, said leaf springaffixed to a termination means; conducting means afiixing saidconducting arm and said leaf spring to said nylon arm portion, and astationary contact afiixed to an ear of a support bracket for saidignition breaker.

5. An ignition contact set comprising: a support bracket having a pivotpost extending upwardly therefrom and rigidly fastened thereto; anon-conductive pivot arm having a first and a second end, said first endterminating in a split bushing adapted to circumferentially engage saidpivot post, said second end terminating in a cam follower portion;resilient retaining means urging said split bushing against said pivotpost; a conductive arm portion affixed to said non-conductive pivot armso as to extend outwardly beyond said second end, said conductive armportion terminating in a moveable contact; a stationary contact mountedon said support bracket adjacent to said moveable contact; a conductiveleaf spring having a first and second end and a main body portion, saidfirst end affixed to said non-conductive pivot arm and said conductivearm portion so as to be in electrical contact with said moveablecontact, said second end afl'ixed to a terminating means for saidignition contact set, said main body portion looped around said splitbushing in a spaced apart relationship therewith so as to urge saidmoveable contact against said fixed contact.

6. An ignition contact set comprising: a support bracket having a pivotpost extending upwardly therefrom and rigidly fastened thereto; anon-conductive pivot arm having a first and a second end, said first endterminating in a split bushing adapted to eircumferentially engage saidpivot post, said second end terminating in a cam follower portion;spring clip means urging said split bushing against said pivot post,said spring clip means circumferentially disposed about said splitbushing; a conductive arm portion affixed to said non-conductive pivotarm so as to extend outwardly beyond said second end, said conductivearm portion terminating in a moveable contact; a stationary contactmounted on said support bracket adjacent to said moveable contact; aconductive leaf spring having a first and second end and a main bodyportion, said first end afiixed to said non-conductive pivot arm andsaid conductive arm portion so as to be in electrical contact with saidmoveable contact, said second end aifixed to a terminating means forsaid ignition contact set, said main body portion looped around saidsplit bushing on a spaced apart relationship therewith so as to urgesaid moveable contact against said fixed contact.

7. An ignition contact set comprising: asupport bracket having a pivotpost extending upwardly therefrom and rigidly fastened thereto; anon-conductive pivot arm having a first and a second end, said first endterminating in a hollow cylindrically-shaped bushing adapted tocircumferentially engage said pivot post, said ho'llowcylindrically-shaped bushing having an axially extending split in thewall thereof, said second end terminating in a cam follower portion;resilient retaining means urging said split bushing against said pivotpost, a conductive arm portion affixed to said non-conductive pivot armso as to extend outwardly beyond said second end, said conductive armportion terminating in a moveable contact; a stationary contact mountedon said support bracket adjacent to said moveable contact; a conductiveleaf spring having a first and second end and a main body portion, saidfirst end affixed to said non-conductive pivot arm and said conductivearm portion so as to be in electrical contact with said moveablecontact, said second end affixed to a terminating means for saidignition contact set, said main body portion looped around said splitbushing in a spaced apart relationship therewith so as to urge saidmoveable contact against said fixed contact.

8. An ignition contact set comprising: a support bracket having a pivotpost extending upwardly therefrom and rigidly fastened thereto; anon-conductive pivot arm having a first and a second end, said first endterminating in a hollow cylindrically-shaped bushing adapted tocircumferentially engage said pivot post, said hollowcylindrically-shaped bushing having an axially extending split in thewall thereof, said second end terminating in a cam follower portion;spring clip means urging said split bushing against said pivot post,said spring clip means circumscribing more than degrees of said splitbushing; a conductive arm portion affixed to said non-conductive pivotarm so as to extend outwardly beyond said moveable contact; a conductiveleaf spring having a first and a sec-0nd end and a main body portion,said first end affixed to said non-conductive pivot arm and saidconductive arm portion so as to be in electrical contact with saidmoveable contact, said second end afiixed to a terminating means forsaid ignition contact set, said main body portion looped around saidsplit bushing in a spaced apart relationship therewith so as to urgesaid moveable contact against said fixed contact.

References Cited by the Examiner UNITED STATES PATENTS 1,817,160 8/1931Morison 308-63 2,696,534 12/1954 Mallory 20030 2,835,755 5/1958 Filko200-30 2,851,314 9/1958 Thomson 30871 X 2,857,214 10/1958 Kogstrom et al30871 2,962,770 12/ 1960 Ingraham 308-238 X ROBERT K. SCI-IAEFER,Primary Examiner.

H. O. JONE Assistant Examiner.

1. IN AN IGNITION BREAKER, A PIVOT ARM COMPRISING: A NON-CONDUCTIVE ARMPORTION HAVING A FIRST END AND A SECOND END; SAID FIRST END TERMINATINGIN A SPLIT BUSHING, SAID SPLIT BUSHING CIRCUMFERENTIALLY ENGAGING APIVOT POST; RESILIENT MEANS URGING SAID SPLIT BUSHING AGAINST SAID PIVOTPOST; SAID SPLIT BUSHING ADAPTED TO PIVOTALLY SUPPORT SAID PIVOT ARM ONSAID PIVOT POST; SAID SECOND END TERMINATING IN A CAM FOLLOWER, SAID CAMFOLLOWER EXTENDING DOWNWARDLY FROM SAID PIVOT ARM; AND A CONDUCTIVE ARMPORTION COOPERATING WITH SAID NON-CONDUCTIVE ARM PORTION.